Anthony
Pettis has suffered a knee injury that will not allow him to
challenge Jose Aldo for
the UFC featherweight title.

UFC President Dana White announced the news on Friday, revealing
that Aldo will now defend his belt against Chan Sung
Jung in the UFC
163 main event. Jung was initially booked to face Ricardo
Lamas on July 6 at < a
href="http://www.sherdog.com/events/UFC-162-Silva-vs-Weidman-28459">UFC
162; it is currently unknown if Lamas will remain on that bill.

The new headliner tops the Aug. 3 card, which takes place at the
HSBC Arena in Rio de Janeiro and also features a light heavyweight
confrontation pitting ex-champion Lyoto
Machida against Phil
Davis.

Commonly known as “The Korean Zombie,” Jung has won three straight
fights since suffering back-to-back defeats to Leonard
Garcia and George Roop
to cap his World Extreme Cagefighting career. The 26-year-old
avenged his controversial loss to Garcia in his UFC debut,
submitting the brawler with a twister at Fight Night 24. Two more
victories would follow for the South Korean, who knocked out former
title challenger Mark
Hominick in just seven seconds to close out 2011 before
submitting Dustin
Poirier with a brabo choke just over one year ago in Sherdog’s
2012 “Fight of the Year.”

Aldo, meanwhile, last competed on Feb. 2, when he took a
hard-fought unanimous decision from ex-lightweight ruler Frankie
Edgar at UFC 156. “Scarface” has not lost in more than seven
years and owns a 4-0 UFC record, successfully defending his title
against Hominick, Kenny
Florian, Chad Mendes
and Edgar.